Induction-motor control.



PATENTED NOV. 6, 1906.

M. G. A. LATOUR.

INDUCTION MOTOR CONTROL.

APPLIOATION FILED MAR.2'7.1905.

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lm enfoi. C4 Lafbui? Mar/Z16 NON/1166866 MW No. 835,444. PATENTED NOV. 6, 1906. M. c; A. LATOUR.

INDUCTION MOTOR CONTROL.

APPLICATION FILED MAR.27.1905.

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UNITED STATES MARIUS C. A. LATOUR, OF PARIS,

PATENT OFFICE,

FRANCE, ASSIGNOR TO GENERAL INDUCTION-MOTOR CONTROL.

No. 83 5,444. Specification of Application filed March 27.

To all whom it may concern.-

Be it known that I, MARIUs C. A. LATOUR, a citizen of France, residing at Paris, France, have invented certain new and useful I1nprovement-s in Induction-Motor Control, of which the following is a specification.

My invention relates to the control of induction-n'iotors; and its object is to provide} means for obtaining a plurality of speeds with such motors when supplied with current of a given frequency without the use of resistances in the secondary circuit. In induction-motors the rotor speed is determined by the speed of the revolving field, the resistance of the secondary circuit, and the load upon the motor. With a constant resistance in the rotor-circuit and a constant loadon the motor the speed is determined by the number- Of poles produced by the stator-winding, since the number of poles determines the speed with which the field flux revolves.

My invention consists in the method of controlling an induction-motor which consists in gradually varying the speed at which the field-flux revolves, or, more specifically stated, it consists'in gradually shifting the terminal connections of the primary winding in passing from one number of poles to another, so-that a plurality of speeds are obtained intermediate the speeds which are obtained when the motor is connected first for one and then for another number of poles.

My invention will best be understood by reference to the accompanying drawings, in which- Figure 1 shows, somewhat diagrammatically, an induction-motor and controllingswitch arranged in accordance with my invention; and'Figs. 2 to 6 represent diagrammatically the motor connections produced by the controlling-switch in its several positions.

Referring first to Fig. 1, S represents the stator of an inductionm0tor which, for the sake of simplicity, I have shown as of the Gramme-ring type. It will be understood, however, that other wellknown forms of winding, such as a drum-Winding, arranged in slots on the inner periphery of the field structure, may be used. R represents the rotor or secondary member, which I have indicated as a short-circuited squirrel-cage. 1, 2, and 3 represent three leads from a source of three-phase current to which the stator of Letters Patent. Patented Nov. 6, 1906.

1901;. Serial it. 252,212.

' the motor is connected through the controlling-switch F. g

\Vhen the controlling-switch is in the first of its positions, as indicated by the. dotted lines, the following circuits are established:

, line-wire 1 is connected through contact-fingerf and cont act-finger f 4 to the motor-terminal A and through the fingers f 3 and f to the motor-terminal A and through the fingers f and f to the motor-terminal A Similarly, line-wire 2 is connected to the motor-terminals-B,, B and B,,'while the linewire 3 is connected to the motor-terminal C,, C.,, and C Themotor is thus connected as a six-pole three-phase induction-motor. This connection is indicated diagrammatically in Fig. 2, the motorterminals which are not in circuit being omitted. In moving to the second position the controlling switch breaks the connections from the source to motorterminals A B and C at the contacts f f and f respectively, thereby establishing the connections shown in Fig. 3. Although three of the motor-terminals are thus open-circuited and the motor is connected as an asymmetrical four-pole motor, it still operates as a six-pole motor, since the speed of rotation of the flux as determined by the part of the stator-winding still connected to the source is the same as before, the remaining part of the stat or-winding being practically idle as far as its effect upon the rotor speed is concerned. In movingfrom the second to its third posi tion, tln circuit of terminal A is broken at contact-finger f and a' circuit is established by the contact-finger f from line-wire 1 to motor-terminal A, Similarly, the connec tions from linewire 2 are shifted from terminals 13,, and B to B and B',,, while the connections from line-wire 3 are shifted from C and C to C and C, These connections are indicated-in Fig. 4. The relative distance between the motor-terminals is the speed of rotation of the flux and.the speed of the rotor, although the number. of oles is not changed. In moving to its ourth osition the controlling-switch F f and establishes 'a connection through finger f 9 to terminal A Similarly, the con- B, and]?! v to B and B while the conbreaks .t e connection of contact A, at finger nections from line-wire 2 are shifted from consequently increased, thereby increasing terminal happens to be the same as terminal 1 1 White connection "from line-wire 3 is shifted from terminal 0'', and C, to 0", and C terminai U, being the same as terminal A,. These connections, which were shown in Fig. e, are the usual symmetricalcormeetions for a four-polemotor, and

seed as compared with the connection s own in 2 18 increased in the ratio of 2'to 3.

By my invention it is rendered possible to obtain not only the speed corresponding to the us" at sin-pole and four-pole connections, but nice varying the distance between poise Wit t changing their number to secnre a pints y of intermediate speeds not olt tainaliie with the methods of speed control ernpllo yed heretoi ore.

d not desire to iimit rr'i-yseii to the partics construction and arrangement of parts here shown, hut aim the a pended claims to cover all modifications W ch are w'itlilin scope of my invention.

What it claim as new, and desire to secure Letters Patent of the United States, is

11. The method of controlling an inductionmotor to obtain speeds intermediate the speeds corresponding to two different numbers oi poies, which consists supplying to the motor-terinin-als alternating current of const nt frequency and gradually varying the of rotation oi the field flux by shiftosition of the without changing their nnmoer.

The method oi controlling an inductionmotor obtain speeds intermed ate the speeds correspo i g to two difierent mim .loers oi poies, whic consists in varying the distance between poles without varying their nnmher. 1

The method of increasing the speed of a mnitipoiar indnetionmotor, which consists in breaking the connections them the source to one of primary terminal-s then grednaiiy shifting the rerruslning terminals tiii asymmetrieai terminal] arrangement is reached.

. 3. The method oi increasing the speed of a mnitipoisr induction-motor which consists iii-removing one pair of poles then gradpoles, then breaking the connection to a pormotor, which consists in connecting a source of current to a number of symmetrically-arranged points on the primary winding of the motor so as to produce a definite number of tion of said points, and then gradually s ift ing the remaining points of connection until the points of connection are again symmetrical.

6. In combination, an induction-motor having a primary winding provided with ter minal connections for producing different pole numbers and intermediate taps between said terminals, and a, controlling-switch in circuit with said taps.

7. In combination, an induction-motor having a primary winding provided with terminal connections for producing different pole numbers and intermediate taps between said, terminals,- and a controlling-switch adaptedto connect eitherset of terminals or the intermediate taps to a source of current.

.8. ,In combination, an induction-motor having a primary Winding provided with ter minal connections for producing different poie numbers and intermediate taps between said terminals and a controlling-switch hav ing its contacts arran 'ed to connect a set of terminals tor one num er of poles to a source of current, then tobreak said connections and to connect the intermediate taps successively to the source, and finally to connect the terminals for the second number of poles to the source.

9. In combination, an indnction-motor having a primary winding provided with terminal connections -[or producing diii'erent pole numbers and intermediate taps unsymmetricsily arranged between said terminals, and a controlling-switch adapted to connect either set oi terminals or said taps to a source oi current.

10. in combination, an induction-motor having a primary winding provided with terminal connections for producing v0 diii'erent pole numbers and intermedis aps corresponding in number to the to iii for the smaller number of poles bi" metricaily laced, and a s itch connect cit. or set of terminals or s a source of current.

In witness whereof l have here hand this 14th day of Which, 1905.

' MARIUS C. A. LATUUR.

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